As infection is a leading cause of morbidity and mortality in cancer patients with compromised host defenses, this project was designed to detect the presence of infectious agents in these patients prior to and during infection, and to detect carriers and "shedders" who might transmit infectious agents to them. In addition it affords microbiological data for a number of protocols which involve infection in cancer patients. To provide such data all patient samples are studied intensively and all of the microorganisms recovered are identified as to genus and species. Surveillance cultures taken from high risk patients provide data on patient flora at admission and subsequent acquisition during the hospital stay.